Pen needle and safety shield system

ABSTRACT

A safety shield system for a needle cannula of a pen needle injector or similar device, wherein the safety shield may be retracted from a first position enclosing the needle to a second position exposing the needle for injection. The safety shield system permits retraction of the safety shield during use, but extends the shield enclosing the needle in a locked position following use. The shield system is utilized with a pen needle injector having a double ended needle cannula mounted in a hub received on the open end of the pen needle injector. The assembly is disposed of by removing the assembly and needle cannula hub and storing the assembly in the cup-shaped cap enclosing the exposed end of the needle cannula within the cap. The cap includes internal radial ribs preventing retraction of the shield prior to removing the cap preventing inadvertently piercing the cap during assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.10/072,691, filed on Feb. 2, 2002, which claims priority to PCTApplication No. PCT/US01/23367 filed Jul. 25, 2001, which claimspriority to U.S. Provisional Application No. 60/222,454 filed Aug. 2,2000.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to an improved pen needle and safetyshield system particularly, but not exclusively, adapted for peninjectors. The safety shield system of this invention includes aretractable generally tubular shield which is spring biased to normallyenclose the needle cannula of a pen needle dispenser, but which locks inthe extended position enclosing the needle cannula following injection.Further, the double ended needle cannula assembly may be safely nestedin the cup-shaped cap following injection for disposal.

Hypodermic syringes have been used for many years to deliver selecteddoses of fluids including liquid medicaments, inoculations, etc. topatients. However, many applications using hypodermic needles areself-administered, including, for example, insulin, anti-histamines, etcetera. The required manipulation of a standard prior art hypodermicsyringe can be inconvenient, particularly where the injection isself-administered in a public environment. Medication delivery pens orpen injectors have therefore been developed to facilitateself-administration of injections. A typical pen injector includes agenerally tubular body portion resembling a fountain pen which receivesa vial of fluid, such as insulin, anti-histamines, et cetera, having apierceable closure, such as a rubber septum. The pen needle includes ahub generally having a double ended needle cannula including a first endwhich extends into the body portion of the pen injector for piercing theclosure of the vial and a second end used for self-injection of thefluid contained in the vial. The pen needle also generally includes aremovable cup-shaped cap which encloses the second end of the needlecannula prior to use.

Various improvements in pen needles have been developed or proposed bythe prior art since its introduction, including adjustable injectionlength pen needles as disclosed in U.S. Pat. No. 5,944,700 assigned tothe assignee of the present application and safety shield systems forsuch pen needles, wherein the shield is generally cup-shaped includingan open end which receives the body portion of the pen needle and agenerally closed end portion having a central opening which receives thesecond end of the needle cannula when the shield is retracted from afirst position enclosing the second end of the needle cannula to asecond position wherein the needle cannula is exposed for injection. Theassembly may further include a spring that biases the shield to thenormally enclosed first position prior to injection.

Various safety shield systems have also been developed or proposed bythe prior art for conventional hypodermic syringes wherein a tubularshield is spring biased to enclose the needle cannula followinginjection and including safety shields which lock in the extendedenclosed position following injection. Such safety shield systems forconventional hypodermic syringes are operated manually or are springbiased to extend the tubular shield and enclose the needle cannulafollowing injection but all require additional action (active systems,)such as force, to activate as compared to the standard injectionprocess. Hand manipulated safety shield systems may include spiral orcomplicated channel-shaped tracks on an inside surface of the shieldwhich guide the shield during extension of the shield to enclose theneedle cannula and lock the shield in the extended position. However,such complicated track systems may not always be reliable.

A safety shield system for pen needles has not yet been developedwherein the shield initially encloses the second end of the needlecannula prior to use, permits retraction of the shield forself-administration of the fluid in the pen needle dispenser and thenextends and locks the shield in the extended position enclosing theneedle cannula following use. It would also be desirable to simplify theoperation of the shield to eliminate manual manipulation or rotationalmovement of the shield from the retracted position to a locked extendedposition.

One problem with other pen needle accessories, such as hidden needleadapters, has been potential needle sticks to the user during assemblyof the accessory on the pen injector. Because the shield must beretractable for injection and the shield and cap assembly is typicallythreaded on the pen needle dispenser, the natural tendency of the useror patient is to press the cap toward the injector during assembly. Thismay cause the needle to pierce the cap and possibly puncture the userduring assembly. Another problem associated with pen needles has beenthe safe disposal of the hub and double ended needle cannula. It wouldbe most desirable to safely enclose both sharp ends of the needlecannula hub assembly to avoid inadvertent punctures during and followingdisposal. As will be understood, one end of the needle cannula may beenclosed in the cup-shaped cap; however, the other end is exposedfollowing removal of the hub assembly from the pen injector.

The pen needle and safety shield system of this invention solves theseproblems by providing a safety shield which normally encloses the needlecannula prior to use, permits retraction of the safety shield duringinjection and automatically extends and locks the shield in the extendedenclosed position following use. The pen needle of this invention alsoprevents retraction of the shield during assembly of the shield andneedle cannula and hub assembly on the pen injector. Further, theimproved safety shield system of this invention permits safe disposal ofthe hub and double-ended needle cannula assembly following removal fromthe pen injector.

SUMMARY OF THE INVENTION

As set forth above, the improved safety shield system of this inventionis particularly but not exclusively adapted for pen injectors. That is,although the safety shield system of this invention was specificallydesigned for use with pen injectors of the type described herein, thesafety shield system of this invention may also be used with otherdevices including conventional hypodermic needle fluid delivery systems.For ease of description, however, the safety shield system of thisinvention will now be described as a component of a pen injector. As setforth above, such pen injectors generally include a tubular body portionadapted to receive a conventional vial for dispensing a fluid, such asinsulin, anti-histamines, et cetera. A conventional pen needle dispenserfurther includes a needle cannula hub assembly wherein the hub isgenerally cup-shaped including a tubular portion having an open endwhich threadably receives the tubular end portion of the pen injectorand a closed end portion which receives and secures the needle cannula.The tubular portion of the needle hub may be threadably or otherwiseattached to the tubular end portion of the pen injector. The needlecannula extends through the end portion of the hub and includes a firstend portion which extends into the body portion of the pen injector forpiercing the closure in the vial and an opposed second end portion usedfor injection of a patient, including self-injection.

The improved safety shield system of this invention includes a generallytubular clip member preferably having a tubular body portion receivedaround the tubular hub portion of the needle hub assembly and aplurality of spaced laterally projecting resilient fingers. In thepreferred embodiment of the safety shield system of this invention, thefree ends of the resilient fingers are hook-shaped opening toward thebody portion of the pen injector. The safety shield system furtherincludes a generally tubular reciprocable shield having a first tubularportion surrounding the clip member and a second tubular portionnormally surrounding the second end of the needle cannula. As describedbelow, the shield is spring biased to normally extend the second portionof the shield around the needle cannula. The shield further includes aplurality of spaced axially extending inwardly opening channel-shapedtracks on an inner surface of the shield which receive the resilientfingers of the clip member. During reciprocal motion of the shield asdescribed below, the axially extending channel-shaped tracks guide theshield from a first position, wherein the shield second portionsurrounds the second end of the needle cannula, to a second position,wherein the second end of the needle cannula is exposed for injection ofa patient. The safety shield system further includes a springresiliently biasing the shield axially to normally extend the shieldsecond portion to surround the second end of the needle cannula. Thus,during use of the pen injector, the health care worker or patientpresses the end of the shield against the area to be injected, whichretracts the shield to the second position against the force of thespring. In the most preferred embodiment, the shield is cup-shapedincluding the first and second tubular portions described above and agenerally closed end portion having a central opening which receives thesecond end of the needle cannula therethrough during injection.Following use, the spring automatically extends the shield to enclosethe second end of the needle cannula.

At least one of the channel-shaped tracks in the shield includes anopening spaced from but near the open end of the shield, and means isprovided to prevent the free end of the resilient finger from beingreceived in the opening during retraction of the shield from the firstposition enclosing the second end of the needle cannula to expose theneedle cannula as described. Thus, the shield may be retracted to exposethe second end of the needle cannula during injection, but the resilientfinger will lock into the opening when the spring extends the shield toenclose the second end of the needle cannula following injection. Theshield is thereby locked in the first position enclosing the second endof the needle cannula following injection. In the preferred embodiment,wherein the free end of the resilient fingers are hook-shaped asdescribed above, the hook-shaped portion of the finger is receivedthrough the opening and securely locks the shield in the closedposition. In the most preferred embodiment, each of the channel-shapedtracks include an opening which receives and secures each of the lockingfingers. The improved safety shield system of this invention thuspermits one retraction of the safety shield during injection and locksthe safety shield to enclose the second end of the needle cannulafollowing injection. Although various means may be utilized to preventreceipt of the locking fingers in the openings in the channel-shapedtracks during retraction of the safety shield to expose the needlecannula, a preferred embodiment includes a resilient detent or fingerportion in the tracks adjacent the opening which resiliently biases thefingers of the clip member inwardly, such that the resilient fingers ofthe clip member travel past the opening during retraction of the shieldmember to the second position as described above. Further, the resilientdetents catch the hook-shaped end portions of the resilient fingersduring extension of the shield, assuring locking of the shield in theextended position following injection.

The preferred embodiment of the safety shield system of this inventionfurther includes a removable cup-shaped cap which is received over theshield prior to use. As will be understood, the cap is then removed andthe pen injector is ready for use as described above. However, the capof the improved safety shield system of this invention may also be usedto safely store and dispose of the double ended needle cannula. Asdescribed above, the second end of the needle cannula is protectedfollowing injection by the safety shield which is locked in the extendedposition surrounding the second end of the needle cannula. The needlecannula and safety shield system may then be safely stored in the capfor disposal by removing the needle cannula and safety shield assemblyfrom the pen injector and inserting the first end of the needle cannulainto the cup-shaped cap which is configured and adapted to receive andstore the assembly for safe disposal. That is, the first end of theneedle cannula is then located in the cup-shaped cap preventing exposureto the needle cannula and the second end portion is safely enclosed bythe safety shield which is locked in the extended position protectingthe second end of the needle cannula.

The safety shield system of this invention thus provides reliableoperation and protection from the needle cannula. In the preferredembodiment, the generally tubular safety shield moves axially guided bythe axially extending channel-shaped tracks as described above, therebyeliminating rotational movement of the shield or a complex track system.In the most preferred embodiment, the tubular body portion of the clipmember includes a plurality of spaced axially extending radiallyprojecting ribs which are received in axially extending grooves in thetubular portions of the shield, assuring axial movement of the shieldduring retraction and extension of the shield as described above. In themost preferred embodiment, the resilient fingers of the clip memberinclude a U-shaped portion integrally connected to the tubular portionof the clip member and hook-shaped free end portions as described above.This configuration provides additional resiliency for the hook-shapedend portions of the fingers. Further, the U-shaped portion of thefingers preferably open toward the generally closed end of the shieldand the spring includes a first end received in the U-shaped portions ofthe fingers and a second end biased against the generally closed end ofthe shield assuring reliable movement of the shield.

The pen needle and safety shield system of this invention also preventsretraction of the shield during assembly of the safety shield system onthe pen injector. As set forth above, one problem with the prior art penneedles has been potential piercing of the cap during threaded assemblyof the cap and shield assembly on the pen dispenser thereby exposing theuser to puncture. The cap of the improved safety shield system includesa plurality of radially inwardly projecting ribs which are received inthe axially extending grooves in the tubular portion of the shieldagainst the axially projecting ribs on the clip member. The grooves inthe tubular portion of the shield preferably extend through the sidewall of the shield from adjacent the generally closed end to the ribs.These internal ribs on the cap prevent retraction of the shield duringthreaded assembly of the cap and shield assembly on the pen injector,thereby preventing accidental puncture during assembly.

The pen needle and safety shield system of this invention thus permitsnormal operation of the safety shield to retract the shield duringinjection and automatically extends and locks the shield followinginjection to prevent inadvertent contact with the second end of theneedle cannula. Further, as described above, the needle cannula assemblymay then be safely stored in the cup-shaped cap or cover for disposalwherein the first end of the needle cannula is located in the cup-shapedcover and the second end is protected by the safety shield. Otheradvantages and meritorious features of the pen needle and safety shieldsystem of this invention will be more fully understood from thefollowing description of the preferred embodiments, the appended claimsand the drawings, a brief description of which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a preferred embodiment of the pen needle andsafety shield system of this invention with the cap removed;

FIG. 2 is a partial cross-sectional view of the pen needle and safetyshield system of this invention;

FIG. 3 is a side elevation partially cross-section of the safety shieldassembly;

FIG. 4 is a side cross-sectional view of the safety shield;

FIG. 5 is a partial side cross-sectional view of FIG. 1 in the directionof view arrows 5-5;

FIG. 6 is a partial cross-sectional view similar to FIG. 5 during use ofthe pen needle and safety shield assembly for injection;

FIG. 7 is a partial side cross-sectional view similar to FIG. 6following injection; and

FIG. 8 is a side cross-sectional view of the safety shield systemfollowing removal from the pen injector and assembly for safe storage.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As set forth above, the improved safety shield system of this inventionis particularly but not exclusively adapted for pen injectors, such asthe pen needles available from Becton Dickinson & Company best shown at20 in FIGS. 1 and 2. As will be understood, however, the safety shieldsystem of this invention may also be used with other pen injectors ofthis general type and with conventional hypodermic syringes as describedabove.

As described below, the safety shield 22 normally encloses the secondend 38 of the needle cannula 34 as shown in FIG. 2 and the safety shieldassembly 23 is enclosed by a cup-shaped cap 24 as shown in FIG. 1. Thedisclosed embodiment of the pen needle 20 includes an open end 26 whichmay include external ribs 28 to facilitate gripping of the pen needle 20by the user for threaded attachment of the assembly to the pen injectoras described below. As shown in FIG. 2, the pen injector 20 receives avial shown in phantom at 30 having a pierceable closure such as a rubberseptum (not shown) in the open tubular end portion 31 of the vial. Thepen injector 20 further includes a needle cannula and hub assembly 32which includes a needle cannula 34 which extends through the hub member40 to define a first end 36 which extends into the pen injector topierce a closure of a vial 30 or other container and a second opposedend 38 used for injection, including self-administration as describedabove. The hub 40 includes a tubular rim portion 42 which is preferablythreadably received on the tubular end portion 44 of the pen injector 20and a central portion 46 which receives and secures the needle cannula34. As will be understood by those skilled in this art, the needlecannula 34 includes a lumen or small passage therethrough fortransferring fluid in the vial 30 to the user for self-injection oradministration by a health care worker and the tubular rim portion 42 ofthe hub 40 may include internal threads for threaded receipt of the hubon the externally threaded rim portion 44 of the pen injector. Needlecannula and hub assemblies of this general type are well known in thisart and therefore no further description of the needle cannula and hubassembly or the pen injector are required.

The safety shield system of this invention includes a generally tubularclip member 48 having a tubular body portion 50 which is received aroundthe tubular rim portion 42 of the needle hub member 40 as shown in FIG.2 and a plurality of laterally projecting resilient hook-shaped fingers52. The clip member may be formed of a resilient polymeric material,such as polypropylene, such that the fingers are able to flex inwardlyand resiliently flex outwardly as described below. Alternatively, theclip member 48 may be formed of a metal stamping. As shown in FIG. 2,for example, the fingers 52 are supported on a U-shaped portion 54 whichfurther improves the resiliency of the fingers as they flex inwardly andspring outwardly. The clip member further includes a plurality ofcircumferentially spaced radially extending ribs 56 which preventrotational movement of the shield 22 and guide the shield during axialmovement of the shield as described below.

The safety shield 22 is generally tubular having an open end 58 andpreferably including a generally closed end 60 having an axial opening62 therethrough which receives the second end 38 of the needle cannula34 as described below. The shield 22 further includes a plurality ofcircumferentially spaced longitudinally or axially extendingchannel-shaped tracks 64 in an internal surface of the tubular portionof the shield which receives the hook-shaped fingers 52 and a pluralityof circumferentially spaced axially extending slots or grooves 66 whichreceive the radial ribs 56 on the clip. As will be understood, thelongitudinal axis of the safety shield 22 is coincident with the needlecannula 34. In the preferred embodiment, the axial channel-shaped tracks64 each include a radial opening 68 which is generally adjacent to butspaced from the open end 58 of the shield. Each of the axialchannel-shaped tracks 64 also include an inwardly projecting resilientintegral tang or finger portion 70 adjacent the opening 68 closest tothe open end 58 as best shown in FIG. 4. The resilient tangs or fingerportions 70 resiliently bias the hook-shaped fingers 52 inwardly andpreferably include a ledge 72 releasably retaining the shield 22 in theextended position prior to injection as shown in FIG. 2 and furtherdescribed below.

The safety shield system of this invention further includes a coilspring 74 biased between the clip member 48 and the generally closed end60 of the shield resiliently urging the shield toward the extendedposition to enclose the second end 38 of the needle cannula 34 as shownin FIG. 2. In the disclosed embodiment, the inside surface of the shieldincludes a plurality of circumferentially spaced radially projectingribs 76 which centers the coil spring 74 in the shield. Finally, thecup-shaped cap 24 includes an open end 78 which receives the safetyshield assembly 23 and needle cannula and hub assembly 32 as describedbelow and a closed end 80. In the most preferred embodiment, theinternal surface of the cap includes a plurality of radially projectingribs which extend axially from adjacent the closed end 80 to the ends ofthe radial ribs 56 which prevent retraction of the safety shield 22during assembly on the pen injector 20 as described below. The externalsurface of the cap may also include ribs 28 to assist in gripping thecap during assembly of the safety shield assembly 23 on the pen injector20. The closed end 80 of the cap also includes an inwardly projectingdimple 86 which is received in the opening 62 of the shield centeringthe cap on the shield. Other details of the preferred embodiments of thesafety shield assembly will be discussed below in the description of theassembly and operation of the disclosed embodiment of the pen needle andsafety shield system of this invention.

First, the operation of the disclosed embodiment of the pen needle andsafety shield system will now be described. One important advantage ofthe safety shield assembly of this invention is that the safety shieldassembly 23 and the needle cannula and hub assembly 32 may bepreassembled and supplied to the patient or end user as an assemblyready for use. The first step by the patient or end user is then toattach this assembly to the pen injector 20 by threading the tubular rimportion 42 of the needle hub assembly 32 on the tubular end portion 44of the pen injector. As can be seen from FIG. 2, the internal radialribs 84 on the cap 24 which are aligned with the ribs 56 of the clipmember 48 prevent inadvertent depression or retraction of the safetyshield assembly 23 which could drive the second end 38 of the needlecannula 34 through the opening 62 of the shield and puncture the cap,which would expose the end user to the needle. This is an importantimprovement over prior pen needle injectors where the patient or healthcare worker could be inadvertently exposed to the needle duringassembly. The vial 30 may be previously loaded into the pen injector 20and the open end 26 may be closed by an end cap, such that the threadedassembly results in piercing the first end 36 through the closure, suchas a rubber septum, in the open end 31 of the vial 30 as the tubular rimportion 42 of the needle hub is threaded onto the rim portion 44 of thepen injector. Alternatively, the vial 30 may be inserted into the peninjector following assembly.

The cap 24 is then removed from the assembly as shown in FIGS. 1 and 5.The pen needle and safety shield assembly of this invention is thenready for use.

As set forth above, the safety shield assembly 23 of this invention isparticularly, but not exclusively, suitable for pen needle injectorstypically used for self-administration of fluid or liquid drugs,vaccines or medicament, such as insulin, anti-histamines, et cetera.During use, the patient simply depresses the generally closed end 60 ofthe safety shield against the body area to be injected as shown in FIG.6. As shown in FIGS. 2 and 5, the hook-shaped fingers 52 are releasablyretained by the inwardly projecting tangs or finger portions 70 of theshield preventing inadvertent retraction of the shield and providingsome resistance to movement of the shield during injection which isconsidered an advantageous feature of this invention. Further, thefingers 52 are resiliently biased inwardly, such that retraction of theshield when the generally closed end of the shield is pressed againstthe skin causes the fingers 52 to move over the openings 68 and moveinto the channel-shaped tracks 64 during initial retraction of theshield, exposing the second end 38 of the needle cannula which isreceived through the opening 62 of the shield, resulting in injection ofthe patient. Rotation of the shield relative to the needle cannula andhub assembly 32 is prevented by the ribs 56 which follow the axial slotsor grooves 66 assuring axial movement of the shield.

Following injection, the needle 38 is withdrawn from the patient and theshield 22 is simultaneously extended by the coil spring 74, such thatthe second end 38 of the needle cannula is never exposed. The shield isthen extended axially as the needle is withdrawn because the hook-shapedfingers move in the axial channel-shaped track 64 and the radial ribs 56move through the slots or grooves 66. However, upon full extension ofthe shield to enclose the second end 38 of the needle, the hook-shapedfingers 52 are received through the openings 68 and the hook-shapedportion is received around the inwardly projecting tang 70, locking theshield in the extended position as shown in FIG. 7. That is, the shield22 cannot be retracted following injection to expose the second end 38of the needle cannula.

The safety shield assembly 23 may then be removed from the pen injector20 by unthreading the tubular rim portion 42 of the hub member 40 fromthe threaded tubular portion 44 of the pen injector 20 and safelydisposed of directly into a sharps container or by reversing thisassembly and inserting the assembly into the cup-shaped cap 24 as shownin FIG. 8. The first sharp end 36 of the needle cannula is thus safelyreceived in the cup-shaped cap 24 and the second end 38 of the needlecannula is protected by the safety shield 22, which is locked in theextended position, providing for safe disposal of the entire assembly.In the most preferred embodiment, the internal ribs 84 of the cap 24provides an interference fit with the safety shield assembly 23,preventing inadvertent removal of the assembly from the cap and thuspreventing inadvertent exposure to either end of the needle cannula 34following disposal. In the disclosed embodiment, one or more of the ribs84 include a ball-shaped end portion 90 which is received in a socket92, securing the assembly in the cap 24 as shown in FIG. 8.

The improved safety shield assembly of this invention thus providesseveral important advantages over the prior art, particularly peninjectors. First, the safety shield assembly 23 and cap 24 may be easilyattached to the pen injector 20 without inadvertent retraction of thesafety shield assembly 23 on the pen injector and piercing of the cap24, exposing the needle and the patient. This safety feature is providedby the radial ribs 56 on the hub member 40, which engage the internalribs 84 of the cap 24 preventing retraction of the shield duringassembly. Upon removal of the cap, the pen injector may be easilyutilized for self-injection by the patient by depressing the generallyclosed end 60 of the safety shield 22 against the area to be injectedwithout ever exposing the second end 38 of the needle cannula 34 toview. Following injection, the safety shield 22 is automaticallyextended by the spring to enclose the second end 38 of the needlecannula 34 and locked in the extended position by the resilient fingers52 which extend into the openings 68 through the channel-shaped tracks66. The hook-shaped fingers also lock over the resilient integral tangs70. Following use, the safety shield assembly 23 and needle cannula andhub assembly 32 may be easily removed from the pen injector 20 byunthreading the tubular rim portion 42 of the hub member 40 from thetubular rim portion 44 of the pen injector, reversing the assembly, andinserting the first end 36 of the needle cannula into the cap 24,providing for safe disposal of the assembly wherein both ends of thedouble ended needle cannula are safely enclosed, preventing inadvertentcontact with the needle.

As set forth above, the needle cannula and hub assembly 32 is assembledin the safety shield assembly 23 prior to receipt by the end user,wherein the hook-shaped fingers 52 are releasably retained by the ledge72 of the inwardly projecting tangs 70 during assembly of the shield 22on the clip member 48. The cap 24 is assembled on the shield bydisposing the inwardly projecting radial ribs 84 of the cap into theslots 66 in the shield as best shown in FIG. 1, wherein the end portions87 engage the ends of the radial rib portions 56 as best shown in FIG.2. The radial ribs in the disclosed embodiment include a chamfered end57 which guides the ribs into the slot 66 and the radial ribs areconnected to the tubular body portion by web portions 55. Further, thecoil spring 74 is received between the radial ribs and the tubular bodyportion against the web portion 55 as shown in FIG. 2. The radial ribsmay thus be resiliently flexed inwardly during assembly. As set forthabove, the clip member 48 may be formed of a resilient polymericmaterial, such as polypropylene or formed of a metal stamping. All ofthe components of the safety shield assembly 23 and the cap 24 arepreferably formed of a sterilizable material including a polymericmaterial which can be injection molded. Thus, a suitable material forthe cap 24, shield 22 and clip member 48 is a sterilizablepolypropylene.

Having described a preferred embodiment of the pen needle and safetyshield system of this invention, it will be understood that variousmodifications may be made to the disclosed embodiment within the purviewof the appended claims. For example, other locking means for locking theshield 22 in the extended position following injection may be utilized.Further, locking means may be provided within the cap for locking thesafety shield assembly 23 within the cap following removal of the safetyshield assembly from the pen injector 20 and storage of the assembly inthe safety cap as shown in FIG. 8, including interlocking ribs, etc.Further, certain improved features of the safety shield system of thisinvention may be utilized with conventional pen needle and shieldassemblies, including, for example, the radial ribs 84 on the internalsurface of the cap which prevent depression or retraction of the shieldduring assembly of the safety shield and cap on the pen injector asdescribed above. Having described a preferred embodiment of thisinvention, we now claim the invention, as follows.

1. A safety shield system for a needle cannula of a pen injector, said safety shield system comprising: a mount for removably securing said safety shield system to the pen injector; a shield movably secured to said mount, said shield being movable between a first position, in which at least part of the needle cannula is surrounded by said shield, and a second position, in which at least part of the needle cannula is not surrounded by said shield, and a third position, in which the needle cannula is completely surrounded by said shield; a spring positioned between said mount and said shield for biasing said shield axially to said first and said third positions; a lock secured to said mount and in operative engagement with said shield to permit one-time movement of said shield from said first position to said second position, and one-time movement of said shield from said second position to said third position, said lock securing said shield in said third position following movement of said shield from said second position to said third position, said lock being non-depressible by a user so as to prevent subsequent movement of said shield out of said third position thereby locking said shield in said third position following movement of said shield from said second position to said third position.
 2. A safety shield system as recited in claim 1, further comprising a needle cannula secured to said mount.
 3. A safety shield system as recited by claim 1, wherein said shield has a track defined on an inside surface thereof, said track having an opening defined through a sidewall of said shield, said track being sized and shaped to receive said lock, said lock moving in said track as said shield is moved between said first position and said second position, and between said second position and said third position.
 4. A safety shield system as recited by claim 3, wherein said lock comprises a resilient finger having a free end portion that passes freely over said opening defined through said sidewall of said shield as said shield is first moved from said first position to said second position, and wherein said free end portion of said resilient finger passes into said opening when said shield is moved from said second position to said third position so as to lock said shield in said third position following movement of said shield from said second position to said third position.
 5. A safety shield system as recited by claim 1, wherein said first position and said third position are the same.
 6. A safety shield system as recited by claim 1, wherein said shield has a slot defined in a sidewall thereof, said slot extending over a longitudinal length of said shield.
 7. A safety shield system as recited by claim 6, wherein said mount has a rib defined thereon that is sized and shaped to ride in said slot as said shield is moved between said first, said second, and said third positions.
 8. A safety shield system as recited by claim 1, further comprising a removable cup-shaped cap initially received over said shield.
 9. A safety shield system as recited by claim 8, wherein said cup-shaped cap is configured to receive and retain said mount after use, thereby providing for safe disposal of said safety shield system and needle cannula.
 10. A safety shield system as recited by claim 4, wherein said lock has a tubular body portion and wherein said finger includes a U-shaped portion connected to said tubular body portion.
 11. A safety shield system as recited by claim 1, wherein said spring is a coil spring.
 12. A safety shield system as recited by claim 1, wherein said shield is generally cup-shaped having an open end disposed around said mount and a generally closed end having a central opening defined therethrough and through which needle cannula may freely pass as said shield is moved between said first, said second and said third positions.
 13. A pen injector and safety shield assembly, comprising: a pen injector having a generally tubular body portion including an open end; a safety shield assembly removably securable to said open end of said generally tubular body of said pen injector, said safety shield assembly comprising: a mount for removably securing said safety shield system to the pen injector; a needle cannula secured to said mount and having a first end extending into the pen injector body, and a second end extending away from the pen injector body; a shield movably secured to said mount, said shield being movable between a first position, in which at least part of said needle cannula is surrounded by said shield, and a second position, in which said second end of the needle cannula is not surrounded by said shield, and a third position, in which said second end of said needle cannula is completely surrounded by said shield; a spring positioned between said mount and said shield for biasing said shield axially to said first position; a lock secured to said mount and in operative engagement with said shield to permit one-time movement of said shield from said first position to said second position, and one-time movement of said shield from said second position to said third position, said lock securing said shield in said third position following movement of said shield from said second position to said third position, said lock being non-depressible by a user so as to prevent subsequent movement of said shield out of said third position thereby locking said shield in said third position following movement of said shield from said second position to said third position.
 14. A pen injector and safety shield assembly as recited by claim 13, wherein said shield has a track defined on an inside surface thereof, said track having an opening defined through a sidewall of said shield, said track being sized and shaped to receive said lock, said lock moving in said track as said shield is moved between said first position and said second position, and between said second position and said third position.
 15. A pen injector and safety shield assembly as recited by claim 14, wherein said lock comprises a resilient finger having a free end portion that passes freely over said opening defined through said sidewall of said shield as said shield is first moved from said first position to said second position, and wherein said free end portion of said resilient finger passes into said opening when said shield is moved from said second position to said third position so as to lock said shield in said third position following movement of said shield from said second position to said third position.
 16. A pen injector and safety shield assembly as recited by claim 13, wherein said first position and said third position are the same.
 17. A pen injector and safety shield assembly as recited by claim 13, wherein said shield has a slot defined in a sidewall thereof, said slot extending over a longitudinal length of said shield.
 18. A pen injector and safety shield assembly as recited by claim 17, wherein said mount has a rib defined thereon that is sized and shaped to ride in said slot as said shield is moved between said first, said second, and said third positions.
 19. A pen injector and safety shield assembly as recited by claim 13, further comprising a removable cup-shaped cap initially received over said shield.
 20. A pen injector and safety shield assembly as recited by claim 19, wherein said cup-shaped cap is configured to receive and retain said mount after use, thereby providing for safe disposal of said safety shield system and needle cannula.
 21. A pen injector and safety shield assembly as recited by claim 15, wherein said lock has a tubular body portion and wherein said finger includes a U-shaped portion connected to said tubular body portion.
 22. A pen injector and safety shield assembly as recited by claim 13, wherein said spring is a coil spring.
 23. A pen injector and safety shield assembly as recited by claim 13, wherein said shield is generally cup-shaped having an open end disposed around said mount and a generally closed end having a central opening defined therethrough and through which needle cannula may freely pass as said shield is moved between said first, said second and said third positions.
 24. A single-use safety shield system for a needle, said safety shield system comprising: a clip having a resilient finger that is non-depressible by a user, said clip being removably attachable to a pen injector; a shield surrounding said clip and having a first opening through which said needle may pass and a second opening defined in a sidewall thereof, said shield being movable from a first position, in which said shield at least partially surrounds said needle and said resilient finger is visible through said second opening and contained within said shield, a second position, in which said needle extends through said first opening, and a third position in which said shield completely surrounds said needle; said finger freely passing over said second opening as said shield is moved from said first position to said second position, and said finger extending into said second opening when said shield is moved from said second position to said third position to thereby lock said shield in said third position so as to prevent re-use of said single-use safety shield system.
 25. A single-use safety shield system as recited by claim 24, further comprising a spring for biasing said shield toward said first and said third positions.
 26. A single-use safety shield system as recited by claim 24, wherein said resilient finger comprises a visual indicator depicting a pre-use state of said safety shield system, and a post-use state of said safety shield system. 